JP2005268653A - Plasma treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treatment device that can efficiently propagate an electromagnetic wave. <P>SOLUTION: The plasma treatment device treats an object to be treated with plasma by generating the plasma in a vacuum vessel 4 by introducing the electromagnetic wave generated from a high-frequency power source into an electromagnetic wave radiating rectangular waveguide through an electromagnetic wave distributing rectangular waveguide 21, and, at the same time, radiating the electromagnetic wave into the vessel 4 through the slot of a slotted plate 14. The electromagnetic wave distributing rectangular waveguide 21 and electromagnetic wave radiating rectangular waveguide are connected to each other through a hollow third electromagnetic wave transmission line which is formed so that its internal size may become smaller toward the transmission side of the electromagnetic wave. In addition, a dielectric member 42 having a wedge-like shape and arranged to be expanded toward the transmission side is provided in the third electromagnetic wave transmission line. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention includes, for example, a semiconductor element such as a thin film transistor (TFT) or a metal oxide semiconductor element (MOS element), a semiconductor device such as a semiconductor integrated circuit device, or a manufacturing process of a display device such as a liquid crystal display device. The present invention relates to a plasma processing apparatus applied to the above.

  Conventionally, in order to perform plasma processing such as film deposition, surface modification, or etching in a manufacturing process of a semiconductor device or a liquid crystal display device, a parallel plate type high-frequency plasma processing device or an electron cyclotron resonance (ECR) plasma is used. A processing device or the like is used.

  However, the parallel plate type plasma processing apparatus has a problem that the plasma density is low and the electron temperature is high. In addition, since the ECR plasma processing apparatus requires a DC magnetic field for plasma excitation, there is a problem that it is difficult to process a large area.

  In recent years, a plasma processing apparatus that can generate a plasma having a high density and a low electron temperature has been proposed to solve such problems.

  As this type of plasma processing apparatus, an apparatus including a circular microwave radiation plate having slots arranged concentrically is known. In this plasma processing apparatus, the microwave introduced from the coaxial tube toward the center of the circular microwave radiation plate is radiated from the slot while propagating in the radial direction of the circular microwave radiation plate. Thereby, since the microwave is introduced into the vacuum container through the electromagnetic wave radiation window, plasma is generated in the vacuum container (see, for example, Patent Document 1).

  The plasma processing apparatus is configured such that microwaves are supplied into the chamber through a dielectric window from two slots forming a waveguide antenna disposed on the H-plane of a rectangular waveguide. Is known. In this plasma processing apparatus, the slot is narrower as it is closer to the reflecting surface. Further, the slot is formed in a stepped shape or a tapered shape so as to become narrower toward the reflection surface of the waveguide (see, for example, Patent Document 2).

Furthermore, as a plasma processing apparatus, a surface wave plasma apparatus in which a plurality of rectangular waveguides are arranged in parallel at equal intervals is known. Each waveguide is provided with a coupling hole having a coupling coefficient sequentially increased toward the tip side. The vacuum vessel is provided with a plurality of dielectric windows divided and formed corresponding to each coupling hole (see, for example, Patent Document 3).
Japanese Patent No. 2722070 Japanese Patent No. 2857090 JP 2002-280196 A

  However, when a microwave is propagated in a conductor such as a coaxial tube or a circular microwave radiation plate as in the plasma processing apparatus described in Patent Document 1, a propagation loss such as a copper loss occurs in the conductor. This propagation loss increases as the frequency increases and as the coaxial transmission distance and radiation plate area increase. Therefore, even if a plasma processing apparatus corresponding to a relatively large substrate such as a liquid crystal display device is designed using the technique described in Patent Document 1, the microwave attenuation is large and it is difficult to efficiently generate plasma. It is. In addition, since the plasma processing apparatus described in Patent Document 1 is configured to emit microwaves from a circular microwave radiation plate, when applied to a square substrate such as a liquid crystal display device, the corner of the substrate is used. There is also a problem that the plasma becomes non-uniform in the area.

  In addition, as in the case of the plasma processing apparatus described in Patent Document 2, when a microwave propagated in a rectangular waveguide is radiated from two slots, if there are many negative ions in the generated plasma, There is a problem that the ambipolar diffusion coefficient becomes small. Therefore, in the technique described in Patent Document 2, plasma generation is biased to the vicinity of the slot where the microwave is radiated. Further, this plasma bias becomes more prominent when the plasma pressure is high. Therefore, in the plasma processing apparatus described in Patent Document 2, it is difficult to perform plasma processing on a large substrate using a gas containing oxygen, hydrogen, chlorine, or the like that easily generates negative ions as a raw material. If it is high, it becomes even more difficult. Furthermore, since the distribution of the slots constituting the waveguide antenna is localized (not uniform) on the processing surface of the substrate subjected to plasma processing, the plasma density tends to be non-uniform.

Moreover, in the technique described in Patent Document 1 or 2, the electromagnetic wave emission window (dielectric window) has a thickness that can withstand a gas pressure difference between substantially atmospheric pressure and a pressure close to a vacuum, that is, a force of about 1 kg / cm ^2. It is necessary to design for (strength). This is because, in the case of performing plasma processing, generally, after the vacuum vessel (chamber) is once evacuated, process gas or the like is introduced into the vacuum vessel. Therefore, when designing a plasma processing apparatus that performs plasma processing on a large substrate of 1 m square using the technique described in Patent Document 1 or 2, the thickness of the electromagnetic wave transmission window made of synthetic quartz or the like is very large. It is not practical because it becomes thicker.

  Furthermore, in the technique described in Patent Document 3, since the waveguides are spaced apart from each other, it is difficult to uniformly distribute the coupling holes so as to correspond to the entire surface of the substrate to be processed. . Further, since it is necessary to provide a seal for sealing the vacuum as many as the number of coupling holes, the structure of the vacuum vessel is likely to be complicated. In addition, since the processing cost of the top plate of the vacuum vessel increases, there is a problem that the apparatus price increases.

  Accordingly, the applicant of the present application has described a waveguide as a plasma processing apparatus that has a simple structure and can perform plasma processing satisfactorily even on a target object such as a rectangular substrate or a large-area substrate. The thing provided in the vacuum container was proposed (refer Japanese Patent Application 2002-366842 specification).

  By the way, the above Japanese Patent Application No. 2002-366842 describes an example in which the inside of the waveguide is filled with a dielectric member in order to suppress the penetration of plasma into the waveguide. However, if the inside of the waveguide is filled with a dielectric member and the waveguide provided in the vacuum vessel and the oscillator that oscillates electromagnetic waves are coupled via the waveguide provided outside the vacuum vessel, the vacuum vessel A part of the electromagnetic wave is reflected at the boundary between the outer waveguide and the waveguide in the vacuum vessel, and the transmittance of the electromagnetic wave decreases. For example, when the inside of the waveguide outside the vacuum vessel is filled with air (dielectric constant ε = 1) and the inside of the waveguide inside the vacuum vessel is filled with quartz (dielectric constant ε = 3.8), When a plane wave is perpendicularly incident, the transmittance is about 80%.

  The present invention has been made based on such circumstances, and an object of the present invention is to provide a plasma processing apparatus capable of efficiently propagating electromagnetic waves.

  The plasma processing apparatus according to claim 1 of the present invention has a processing container, an oscillator that oscillates an electromagnetic wave, a first electromagnetic wave transmission path, and an inner dimension smaller than that of the first electromagnetic wave transmission path. And a second electromagnetic wave transmission path having a dielectric member provided therein, and an electromagnetic wave radiation section that is provided in the second electromagnetic wave transmission path and radiates an electromagnetic wave in the processing container. The electromagnetic wave generated in is introduced into the second electromagnetic wave transmission line via the first electromagnetic wave transmission line and is radiated into the processing container by the electromagnetic wave radiation unit, thereby entering the processing container. A plasma processing apparatus for generating plasma and performing plasma processing using the plasma, wherein the first electromagnetic wave transmission line and the second electromagnetic wave transmission line are formed in an inner shape as they move toward the electromagnetic wave transmission side. It is connected via a hollow third electromagnetic wave transmission line formed so that the method becomes small, and is arranged inside the third electromagnetic wave transmission line so as to expand toward the transmission side. And a wedge-shaped dielectric member.

  In the present invention and the following invention, the “electromagnetic wave transmission path” refers to a line for transmitting electromagnetic waves with high efficiency. Examples of the electromagnetic wave transmission path include a coaxial tube, a waveguide, and a cavity resonator.

  The coaxial tube has a larger loss (propagation loss) than the waveguide, but does not have a cut-off frequency. Therefore, the transmission frequency range is wide and the transmission path can be downsized even when the wavelength is large.

  Since the waveguide does not have a central conductor that causes a loss in the coaxial tube, the loss is small and it is suitable for transmission of high power. However, there is a cut-off frequency and the transmittable frequency range is narrow. Further, the shape is substantially defined by the frequency of the electromagnetic wave to be transmitted.

  The cavity resonator is designed so that a standing wave stands for a specific frequency, and has an effect of strengthening an electromagnetic wave having that wavelength.

  The “electromagnetic radiation portion” refers to a portion that emits an electromagnetic wave transmitted through the electromagnetic wave transmission path to the outside of the electromagnetic wave transmission path. Examples of the electromagnetic wave radiation portion include a slot, a conductor rod, and an electromagnetic horn.

  The shape of the third electromagnetic wave transmission line can be, for example, a substantially conical shape having a taper such that the inner dimension becomes smaller toward the electromagnetic wave transmission side (electromagnetic wave guide direction side). It is not limited to. In consideration of the workability of the third electromagnetic wave transmission line, it is preferably formed separately from the first and second electromagnetic wave transmission lines, but may be formed integrally with the first electromagnetic wave transmission line. Further, it may be formed integrally with the second electromagnetic wave transmission line.

  In order for the electromagnetic wave to be incident on the wedge-shaped dielectric member in a state with little propagation loss (low reflection), the wedge-shaped dielectric member has a wedge shape that expands toward the electromagnetic wave transmission side, For example, the side surface is preferably formed in a wedge shape having a substantially isosceles triangular shape.

  In the plasma processing apparatus according to the first aspect of the present invention, since the dielectric member is provided inside the second electromagnetic wave transmission path, the plasma is prevented from entering the first and second electromagnetic wave transmission paths. Can be suppressed.

  In addition, in the plasma processing apparatus according to claim 1 of the present invention, the first electromagnetic wave transmission path and the second electromagnetic wave transmission path are formed so that the inner dimensions thereof become smaller toward the electromagnetic wave transmission side. They are connected via a hollow third electromagnetic wave transmission line that also functions as a connection mechanism. For this reason, it is possible to suppress the reflection of the electromagnetic wave generated by the change in the area of the inner shape of the electromagnetic wave transmission line between the first electromagnetic wave transmission line and the second electromagnetic wave transmission line.

  In general, when an electromagnetic wave transmitted through the air is incident on the dielectric member, an angle θ (0 ° ≦ θ ≦ 90 °, hereinafter, θ is formed between the end surface of the dielectric member and the transmission direction of the electromagnetic wave. The larger the angle is, the easier it is for electromagnetic waves to be reflected at the end face.

  In the plasma processing apparatus described in Japanese Patent Application No. 2002-366842, the dielectric member in the waveguide is disposed so that the end face thereof is orthogonal to the transmission direction. That is, since the incident angle θ when the electromagnetic wave transmitted through the air is incident on the dielectric member in the waveguide is approximately 90 °, the electromagnetic wave is at the end face of the dielectric member, that is, the air and the dielectric member. It is relatively easy to be reflected at the interface.

  On the other hand, in the plasma processing apparatus according to claim 1 of the present invention, an electromagnetic wave transmission side is provided inside the third electromagnetic wave transmission line that connects the first electromagnetic wave transmission line and the second electromagnetic wave transmission line. A wedge-shaped dielectric member formed so as to expand toward is provided. By doing so, since the incident angle θ when the electromagnetic wave transmitted through the air enters the wedge-shaped dielectric member can be made less than 90 °, the electromagnetic wave is efficiently wedge-shaped dielectric. It can enter into a member.

  In addition, since the wedge-shaped dielectric member has a higher dielectric constant than air, the proportion of electromagnetic waves reflected at the interface between the wedge-shaped dielectric member and the dielectric member in the second electromagnetic wave transmission path is the same as that of air and the first. The ratio of electromagnetic waves reflected at the interface with the dielectric member in the electromagnetic wave transmission path 2 is extremely small. Therefore, the electromagnetic wave transmitted through the first electromagnetic wave transmission line is efficiently incident on the second electromagnetic wave transmission line via the wedge-shaped dielectric member provided inside the third electromagnetic wave transmission line. Can do.

  Therefore, according to the plasma processing apparatus of Claim 1 of this invention, electromagnetic waves can be propagated efficiently.

  A plasma processing apparatus according to a second aspect of the present invention is the plasma processing apparatus according to the first aspect, wherein the wedge-shaped dielectric member has the top side of the transmission of the first electromagnetic wave transmission line. It arrange | positions so that it may be located in the edge part of the side or the area | region of the vicinity.

  By doing so, it is possible to further reduce the amount of reflection of electromagnetic waves reflected at the interface between air and the wedge-shaped dielectric member.

  In addition, it is preferable that the top side of the wedge-shaped dielectric member and the end portion on the transmission side of the first electromagnetic wave transmission path are located on the same plane. However, it is difficult to completely match the top side of the wedge-shaped dielectric member with the end of the first electromagnetic wave transmission line on the transmission side due to errors in manufacturing the device itself or the wedge-shaped dielectric member. It is. Further, even when the top side of the wedge-shaped dielectric member is slightly separated from the end portion on the transmission side of the first electromagnetic wave transmission path, substantially the same effect as that obtained when perfectly matched can be obtained. Therefore, “the wedge-shaped dielectric member is arranged so that the top side thereof is located at the end of the first electromagnetic wave transmission line or the vicinity thereof” means that a manufacturing error, etc. This means that slight deviations are allowed.

  A plasma processing apparatus according to a third aspect of the present invention is the plasma processing apparatus according to the first or second aspect, wherein the wedge-shaped dielectric member or the dielectric member in the second electromagnetic wave transmission path is used. The airtightness of the processing container is maintained.

  For example, when connecting a rectangular waveguide provided outside the processing container of the first electromagnetic wave transmission path and a rectangular waveguide provided on the wall of the processing container of the second electromagnetic wave transmission path In order to keep the processing container airtight, it is necessary to provide a sealing member. The plasma processing apparatus according to claim 3 of the present invention has the rectangular waveguide and the second electromagnetic wave transmission path provided outside the processing container of the first electromagnetic wave transmission path, as described above. It is suitable for the case where the processing container and the first electromagnetic wave transmission path are integrated by connecting a rectangular waveguide provided on the wall of the processing container.

  By doing so, without complicating the configuration of the processing container and the plasma processing apparatus itself, and maintaining the hermeticity of the processing container, the first electromagnetic wave transmission path provided outside the processing container can be used in the processing container. It is possible to satisfactorily introduce the electromagnetic wave into the second electromagnetic wave transmission path provided in.

  In general, the dielectric member is easily damaged and is expensive. On the other hand, by adopting the above-described configuration, the rectangular wave guide in which the second electromagnetic wave transmission path has a region where atmospheric pressure is applied to the wedge-shaped dielectric member or the dielectric member in the second electromagnetic wave transmission path. It can be about the inner dimension of the tube. That is, with this configuration, the load applied to the wedge-shaped dielectric member that also functions as a dielectric member that maintains the hermeticity of the processing container or the dielectric member in the second electromagnetic wave transmission path is relatively reduced. Therefore, damage to the dielectric member can be suppressed.

  In addition, a dielectric member (a wedge-shaped dielectric member or a dielectric member in the electromagnetic wave transmission path) is provided in the third electromagnetic wave transmission path or the second electromagnetic wave transmission path to keep the processing container airtight. Therefore, it is possible to suppress the plasma generated in the processing container from entering the first electromagnetic wave transmission path. Furthermore, it is easy to design the apparatus in consideration of the flow of the process gas and the like, and it is easy to degas and clean the processing container.

  A plasma processing apparatus according to a fourth aspect of the present invention is the plasma processing apparatus according to any one of the first to third aspects, wherein the transmission-side end portion of the first electromagnetic wave transmission line and the first electromagnetic wave transmission path The distance between the end of the second electromagnetic wave transmission line opposite to the transmission side is set to be longer than the wavelength of the electromagnetic wave generated by the oscillator in vacuum.

  By doing so, it is possible to further suppress the reflection of the electromagnetic wave due to the change in the area of the inner shape of the electromagnetic wave transmission path and the reflection at the interface between the air and the wedge-shaped dielectric member.

  A plasma processing apparatus according to a fifth aspect of the present invention is the plasma processing apparatus according to any one of the first to fourth aspects, wherein each of the first and second electromagnetic wave transmission paths is a rectangular waveguide. Has a wave tube.

  By doing in this way, the transmission loss of the electromagnetic wave in the 1st and 2nd electromagnetic wave transmission path can be suppressed. In addition, high power transmission is possible.

  A plasma processing apparatus according to a sixth aspect of the present invention is the plasma processing apparatus according to the fifth aspect, wherein an inner shape dimension of a rectangular waveguide included in the first electromagnetic wave transmission path, and the second The internal dimensions of the rectangular waveguide included in the electromagnetic wave transmission path are set such that the frequency of the electromagnetic wave generated by the oscillator can be transmitted in the fundamental mode in the rectangular waveguide.

When the frequency of the electromagnetic wave can be transmitted in the fundamental mode in the rectangular waveguide, for example, the dielectric constant of the rectangular waveguide is ε, the major axis of the inner dimension of the rectangular waveguide is a, and the wavelength λ of the electromagnetic wave When
(Λ / ε ^0.5 ) <2a (1)
This can be realized by designing so as to satisfy the above condition.

  As described above, the inner dimensions of the rectangular waveguide included in the first electromagnetic wave transmission line and the inner dimensions of the rectangular waveguide included in the second electromagnetic wave transmission path are respectively determined by the frequency of the electromagnetic wave generated by the oscillator. By enabling transmission in the fundamental mode in the rectangular waveguide, it is possible to reduce the transmission loss amount of the electromagnetic wave in each rectangular waveguide.

  A plasma processing apparatus according to a seventh aspect of the present invention is the plasma processing apparatus according to the fifth or sixth aspect, wherein the length of the top side of the wedge-shaped dielectric member is the second electromagnetic wave transmission. The rectangular waveguide has a length substantially the same as the length of the long side of the rectangular waveguide, and the wedge-shaped dielectric member has the top side of the second electromagnetic wave transmission. It is substantially parallel to the long side direction of the inner diameter of the rectangular waveguide included in the path, and is substantially arranged on a line connecting the midpoints of the short sides.

  By doing so, the electromagnetic wave transmitted through the first electromagnetic wave transmission path is more efficiently transmitted through the wedge-shaped dielectric member provided inside the third electromagnetic wave transmission path. Can be incident on the road.

  The plasma processing apparatus according to claim 8 of the present invention is the plasma processing apparatus according to any one of claims 1 to 7, wherein the wedge-shaped dielectric member has a length along an electromagnetic wave transmission direction. Is set to be longer than the wavelength of the electromagnetic wave generated by the oscillator in vacuum.

  By doing so, it is possible to further suppress the reflection of the electromagnetic wave due to the change in the area of the inner shape of the electromagnetic wave transmission path and the reflection at the interface between the air and the wedge-shaped dielectric member.

  A plasma processing apparatus according to a ninth aspect of the present invention is the plasma processing apparatus according to the first aspect, wherein the wall of the processing container has at least a part of the second electromagnetic wave transmission path. .

  According to the plasma processing apparatus of the ninth aspect of the present invention, since the wall of the processing container has at least a part of the second electromagnetic wave transmission path, the configuration of the processing container and the plasma apparatus itself is simplified. be able to. In addition, by adjusting the shape and arrangement of the second electromagnetic wave transmission path, stable and uniform plasma can be generated in the processing container regardless of the size and shape of the processing container. Therefore, even a target object such as a square substrate or a large-area substrate can be plasma-processed satisfactorily.

  When carrying out the plasma processing apparatus according to claim 9 of the present invention, at least a part of the second electromagnetic wave transmission path can be provided, for example, in the wall of the processing container. That is, in the plasma processing apparatus according to claim 9 of the present invention, for example, by providing a tunnel-like space that penetrates the wall along the wall, the second electromagnetic wave transmission path is formed in the wall of the processing container. Can be provided.

  However, considering the ease of processing the wall, etc., a processing container having a processing chamber in which the object to be processed is plasma-treated is adopted, and at least a part of the second electromagnetic wave transmission path is made of the processing container wall. Preferably, it is provided on the inner surface of the wall defining the processing chamber. In this case, since at least a part of the second electromagnetic wave transmission path can be defined by the inner surface of the wall of the processing container, rather than providing a part of the second electromagnetic wave transmission path so as to penetrate the wall of the processing container. A part of the second electromagnetic wave transmission path can be easily provided on the wall of the processing container.

  Further, when at least a part of the second electromagnetic wave transmission path is provided on the inner surface of the wall that defines the processing chamber of the walls of the processing container, at least a part of the second electromagnetic wave transmission path is defined on the inner surface of the wall. In addition, a slot plate having a plurality of slots may be employed as the electromagnetic wave radiation portion, and the recess may be covered from the processing chamber side by the slot plate. At this time, the plurality of slots are made to correspond to the recesses, respectively. By doing in this way, the 2nd electromagnetic wave transmission line can be provided in the space enclosed by the wall surface and slot plate which define a crevice. In addition, the electromagnetic wave transmitted through the second electromagnetic wave transmission path can be radiated into the processing chamber through the slot.

  In addition, when a recess that defines at least a part of the second electromagnetic wave transmission path is provided on the inner surface of the wall and the recess is covered from the processing chamber side by the slot plate, the second electromagnetic wave transmission path is the same as the processing chamber. It will be provided in a closed space. Therefore, electromagnetic waves can be made incident in the processing chamber without providing an electromagnetic wave transmission window made of synthetic quartz or the like in the processing container.

  In other words, the configuration as described above eliminates the need to provide an electromagnetic wave transmission window made of synthetic quartz or the like in the processing container, so that all the sealing mechanisms between the electromagnetic wave transmission window and the electromagnetic wave transmission window and the wall of the processing container are provided. Can be omitted. Therefore, the configuration of the processing vessel and the plasma apparatus itself can be further simplified.

  Moreover, since the electromagnetic wave transmission window itself can be omitted, it is of course unnecessary to consider the strength of the electromagnetic wave transmission window (the thickness of the synthetic quartz window). Therefore, it is possible to easily design a plasma processing apparatus including a large processing container corresponding to a large-scale object to be processed. Moreover, there is no cost increase associated with the increase in size of the electromagnetic wave transmission window. Further, since the influence of the electromagnetic wave transmission window on the propagation of the electromagnetic wave can be eliminated, it is easy to design an apparatus that can uniformly radiate the electromagnetic wave into the processing container. Therefore, it is possible to obtain a plasma processing apparatus capable of performing plasma processing with stable and uniform plasma even for a target object such as a large-area substrate.

  When the inner surface of the wall is provided with a recess that defines at least a part of the second electromagnetic wave transmission path and is configured to cover the recess from the processing chamber side by the slot plate, a coating for covering the slot plate in the processing chamber is provided. A dielectric member may be provided. By doing so, plasma can be generated satisfactorily in the processing chamber by the electromagnetic wave radiated from the electromagnetic wave radiation part.

  By the way, when a covering dielectric member is provided in the processing chamber so as to cover the slot plate, surface wave plasma can be generated in the processing chamber. That is, when a predetermined process gas is introduced into the processing container (inside the processing chamber) and electromagnetic waves are incident on the processing container, the process gas is excited to generate plasma, and the vicinity of the area surface where the electromagnetic waves are incident The electron density in the plasma (near the slot in the processing chamber) increases. As the electron density in the plasma near the region where the electromagnetic wave is incident increases, it becomes difficult for the electromagnetic wave to propagate through the plasma and attenuates within the plasma. Therefore, since the electromagnetic wave does not reach the region away from the vicinity of the region where the electromagnetic wave is incident, the region where the process gas is excited by the electromagnetic wave is limited to the vicinity of the region where the electromagnetic wave is incident. Thereby, surface wave plasma is generated.

  In plasma treatment using surface wave plasma, damage to the object to be processed due to ions can be suppressed. That is, in a state where surface wave plasma is generated, a region where the energy of the electromagnetic wave is applied to cause ionization of the compound is localized in the vicinity of the region where the electromagnetic wave is incident in the processing container. Therefore, the electron temperature in the vicinity of the surface to be processed of the object to be processed can be kept low by providing the object to be processed at a predetermined distance from the region where the electromagnetic wave is incident in the processing container. That is, since an increase in the electric field of the sheath generated in the vicinity of the surface to be processed of the object to be processed can be suppressed, the incident energy of ions to the object to be processed is reduced, and damage to the object to be processed by ions is suppressed.

  Therefore, by providing a covering dielectric member in the processing chamber so as to cover the slot plate, a plasma processing apparatus capable of suppressing ion damage to the object to be processed can be obtained.

  Some processing containers have a lid that can be removed from the container body for cleaning and maintenance of the processing chamber. Thus, in the processing container in which the container main body and the lid are separate, at least a part of the second electromagnetic wave transmission path is provided on the lid rather than providing at least a part of the second electromagnetic wave transmission path on the container main body. It is possible to easily perform the processing and the design of the apparatus for forming the electromagnetic wave transmission path.

  Therefore, when carrying out the plasma processing apparatus according to claim 9 of the present invention, as a processing container having a processing chamber, the container main body having a bottom wall and a peripheral wall, opened to at least one side, and the opening of the container main body are closed. And a wall that defines the processing chamber among the walls of the processing container employs a bottom wall, a peripheral wall, and a lid of the container main body, and at least one of the second electromagnetic wave transmission paths. The portion is preferably provided on the lid of the processing container.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 5.
The plasma processing apparatus 1 of the present embodiment is oscillated by a high frequency power source 2 as an oscillator, transmitted by an electromagnetic wave transmission mechanism 3, and a slot 15a of a slot plate 14 as an electromagnetic wave radiating portion of a vacuum container 4 as a processing container. Plasma is generated in the vacuum vessel 4 by the electromagnetic wave radiated inside, and the object to be processed 5 is subjected to plasma processing by the plasma.

  As shown in FIGS. 2 and 3, the vacuum container 4 includes a container body 11 and a lid 12. The container body 11 has a bottom wall 11a and a peripheral wall 11b and is open upward. The lid 12 covers the container body 11 from above so as to close the opening of the container body 11. That is, the vacuum container 4 includes the bottom wall 11a and the peripheral wall 11b of the container body 11 and the lid 12 as walls. The container body 11 and the lid 12 are kept airtight by an O-ring 13.

  The vacuum vessel 4 has a processing chamber 4a for plasma processing the object 5 to be processed. The processing chamber 4a is defined by a wall that the vacuum vessel 4 has. In other words, the processing chamber 4 a is defined by the inner surface of the bottom wall 11 a and the inner surface of the peripheral wall 11 b of the container body 11 and the inner surface of the lid 12.

  The vacuum container 4 is formed with such a strength that the inside of the processing chamber 4a can be depressurized to a vacuum state or the vicinity thereof. As a material for forming the vacuum vessel 4, for example, a metal material such as aluminum can be used. As will be described later, a metal slot plate 14 as an electromagnetic wave radiation portion and a covering dielectric member 16 covering the slot plate 14 are provided in the processing chamber 4a. A support base 17 that supports the object to be processed 5 is provided in the processing chamber 4 a of the vacuum vessel 4.

  The vacuum container 4 has a gas inlet 18 for introducing a process gas into the processing chamber 4a and a gas exhaust port 19 for exhausting the gas in the processing chamber 4a. Further, the inside of the processing chamber 4 a is communicated with a vacuum exhaust system (not shown) through a gas exhaust port 19. As the vacuum exhaust system, for example, a turbo molecular pump can be used. Therefore, by operating this vacuum exhaust system, the inside of the processing chamber 4a can be exhausted until a predetermined degree of vacuum is reached.

  The electromagnetic wave transmission mechanism 3 is for transmitting an electromagnetic wave, and includes a first electromagnetic wave transmission path 3a, a second electromagnetic wave transmission path 3b, and a first electromagnetic wave transmission path 3a and a second electromagnetic wave transmission path. One or more connecting 3b, for example, three third electromagnetic wave transmission lines 3c, etc. are provided. The first electromagnetic wave transmission path 3a has, for example, one rectangular waveguide 21. Hereinafter, the rectangular waveguide 21 is referred to as an electromagnetic wave distributing rectangular waveguide. The electromagnetic wave distributing rectangular waveguide 21 is connected to the lid 12 of the vacuum vessel 4 and is configured integrally with the wall of the vacuum vessel 4. On the other hand, the second electromagnetic wave transmission path 3b has one or more, for example, three rectangular waveguides 22. Hereinafter, these rectangular waveguides 22 are referred to as electromagnetic wave emitting rectangular waveguides.

  Here, the rectangular waveguide 22 for electromagnetic wave radiation, the slot plate 14, and the dielectric member 16 for covering will be described.

  Of the walls of the vacuum vessel 4, a wall that defines the processing chamber 4 a, for example, the lid 12 has a part of each electromagnetic wave radiation rectangular waveguide 22. That is, a part of each electromagnetic wave radiation rectangular waveguide 22 and the wall constituting the vacuum vessel 4 are integrated. In other words, a part of the tube wall conductor of each electromagnetic wave radiation rectangular waveguide 22 also serves as a wall constituting the vacuum vessel 4.

  Specifically, the inner surface of the lid 12 has three groove-like recesses 23 that are part of the three electromagnetic wave emission rectangular waveguides 22. These recesses 23 are covered by the slot plate 14 from the processing chamber 4a side. In this way, three electromagnetic wave radiation rectangular waveguides 22 are constituted by the three spaces surrounded by the wall surfaces defining the three recesses 23 and the slot plate 14.

  The slot plate 14 is formed of a metal plate material and has a plurality of slots 15a that radiate electromagnetic waves into the processing chamber 4a. These slots 15 a are formed at positions corresponding to the recesses 23. Specifically, the slots 15a are arranged in a checkered pattern, that is, alternately arranged on a pair of virtual lines parallel to each other, thereby forming one slot group 15. In one slot group 15, the vertical pitch and the horizontal pitch between the slots 15a are substantially uniform. The slot plate 14 is provided with three slot groups 15 so as to correspond to the three recesses 23, respectively.

  A coating dielectric member 16 is provided in the processing chamber 4 a so as to cover the slot plate 14. The covering dielectric member 16 can be formed of a dielectric material such as quartz, alumina, and fluororesin, for example. In order to prevent the electromagnetic wave from propagating in the thickness direction of the covering dielectric member 16, the covering dielectric member 16 is ¼ of the wavelength of the electromagnetic wave in the covering dielectric member 16. It is preferable to set a smaller value.

  In order to suppress reflection of electromagnetic waves at the interface between the electromagnetic wave radiation rectangular waveguide 22 and the slot 15a and the interface between the slot 15a and the covering dielectric member 16, a dielectric member is provided in the slot 15a. Is preferred. The dielectric member provided in the slot can be formed of, for example, synthetic quartz, alumina, fluorine resin, or the like.

  As shown in FIG. 2 and FIG. 3, the slot plate 14 and the dielectric member 16 for clothing are screwed to the lid 12 of the vacuum vessel 4 from the inner surface side with male threads as a fixture 26. The fixture 26 is preferably made of a dielectric material. When using a metal fixture as the fixture 26, if the fixture 26 is left exposed to the processing chamber 4a, electromagnetic waves may be disturbed in the vicinity of the exposed portion of the fixture 26. Therefore, when a metal member is used as the fixture 26, the exposed portion is preferably covered with a cap made of a dielectric material. By doing in this way, the disturbance of the electromagnetic waves produced in the vicinity of the exposed part of the metal fixture 26 can be suppressed.

  By the way, it is preferable to set the distance d (see FIG. 1) between the rectangular waveguides 22 for electromagnetic wave radiation in consideration of the degree of plasma diffusion. That is, the lower the pressure of the process gas, the farther the particles diffuse. In a plasma processing apparatus, the pressure of a process gas is generally about 1 Pa or more. When the pressure of the process gas is 1 Pa or more, the interval (pitch) d between the rectangular waveguides 22 for electromagnetic wave radiation is set to 50 cm as an upper limit and corresponds to the assumed pressure of the process gas. Is preferably set. In this way, uniform plasma can be generated in the processing chamber even under conditions where plasma is difficult to diffuse. Note that when the pressure of the process gas is 0.1 Pa or less, the plasma is easily diffused, and therefore the interval d between the electromagnetic wave emission rectangular waveguides 22 may exceed 50 cm.

  The rectangular waveguides 22 for electromagnetic wave radiation are arranged in parallel with each other so that the distance d is 50 cm or less. More specifically, the position of the electromagnetic wave radiation rectangular waveguide 22 may be set as follows.

That is, the angular frequency of the electromagnetic wave emitted from the high-frequency power source 2 is ω, the dielectric constant of the covering dielectric member 16 is ε _d , the speed of light is c, the electron charge is e, the dielectric constant of vacuum is ε ₀ , the electron density the _{n e,} when the electron mass and _{m e,} plasma angular frequency omega _P is
ω _P = (e ² × n _e / (ε ₀ × m _e )) ^0.5 (2)
And the wave number k is
k = ω / c ((ε _d (ω _p ² −ω ² )) / (ω _p ² − (1 + ε _d ) ω ² )) ^0.5 (3)
Is required.

With respect to the inner dimension L (see FIG. 2) in the direction in which the wave number k is orthogonal to each rectangular waveguide 22 of the vacuum vessel 4,
k = mπ / L (m is an integer of 1 ≦ m ≦ 2L / (λ / ε ^0.5 )) (4)
The distance d of the electromagnetic wave radiation rectangular waveguide 22 is
λ _swp = π / k (5)
Is preferably equal to the wavelength λ _{swp of the} standing wave guided by. At this time, the electromagnetic wave radiation rectangular waveguide 22 is disposed at a position where the amplitude of the standing wave is substantially maximized.

  In order to prevent the plasma from entering the second electromagnetic wave transmission line 3b from the slot 15a, the electromagnetic wave emitting rectangular waveguide 22 has a substantially entire area inside the dielectric member 31 for the electromagnetic wave transmission line. Is filled with. The dielectric member 31 provided in the electromagnetic wave radiation rectangular waveguide 22 can be formed of a dielectric material such as quartz, alumina, and fluororesin. In the present embodiment, the dielectric member 31 is made of synthetic quartz. In addition, you may provide the dielectric material member 31 only in a part of 2nd electromagnetic wave transmission path 3b.

  These dielectric members 31 can be provided inside the electromagnetic wave radiation rectangular waveguide 22 by, for example, the following. First, a rectangular column-shaped elongated dielectric member 31 is formed in advance. The dielectric member 31 is fitted in each recess 23. Thereafter, the slot plate 14 and the covering dielectric member 16 are laminated in this order on the inner surface of the lid 12, and these are fixed to the lid 12 by the fixture 26. Thus, the dielectric member 31 is accommodated in the electromagnetic wave radiation rectangular waveguide 22.

Inner shape of the electromagnetic wave radiating rectangular waveguide 22 (sectional shape), for example, as shown in FIG. 2, the depth direction length x ₁ forms the short horizontally oblong than the width direction length x ₂ ing. That is, in the electromagnetic wave emission rectangular waveguide 22 formed in this way, the bottom surface of the recess 23 and the top surface of the slot plate 14 become surfaces (H surfaces) perpendicular to the electric field direction of the electromagnetic wave, respectively. A surface rising vertically from the bottom surface is a surface (E surface) parallel to the electric field direction of the electromagnetic wave. That is, in the plasma processing apparatus 1 of the present embodiment, the slot 15a is provided in a region corresponding to the H surface of each electromagnetic wave radiation rectangular waveguide 22.

Incidentally, the inner shape of the electromagnetic wave radiating rectangular waveguide 22 (sectional shape), may be formed long longitudinal rectangular shape than the depth direction of the length x ₁ of the width direction length x _2. In the electromagnetic wave emission rectangular waveguide 22 formed in this way, the bottom surface of the recess 23 and the top surface of the slot plate 14 become E planes parallel to the electric field direction of the electromagnetic wave, and downward from the bottom surface of the recess 23. The surface that rises vertically becomes the H surface perpendicular to the electric field direction of the electromagnetic wave. Therefore, by doing so, it is possible to obtain a plasma processing apparatus in which a slot 15a is provided in a region corresponding to the E surface of each electromagnetic wave radiation rectangular waveguide 22.

Next, the electromagnetic wave distribution rectangular waveguide 21 will be described.
The electromagnetic wave distributing rectangular waveguide 21 is provided outside the vacuum vessel 4. The electromagnetic wave distribution rectangular waveguide 21 is bent at a right angle so that the propagation direction of the electromagnetic wave changes by 90 ° from the tube main body 21a and a tube main body 21a extending in a direction orthogonal to the respective electromagnetic wave emission rectangular waveguides 22. The three distribution pipe portions 21b are formed so as to distribute the electromagnetic waves whose propagation directions are changed by 90 ° to the respective electromagnetic wave radiation rectangular waveguides 22 respectively. In addition, the flange 21c is provided in the front-end | tip part (end part by the side of electromagnetic wave transmission) of each distribution pipe part 21b (refer FIG. 4).

The inner shape of the electromagnetic wave distribution for rectangular waveguide 21 (sectional shape) is formed in a short rectangular shape than the depth direction of the length y ₁ of the width direction length y _2. Accordingly, in this electromagnetic wave distribution rectangular waveguide 21, the bottom surface and the top surface are surfaces (H surfaces) perpendicular to the electric field direction of the electromagnetic wave, and the pair of side surfaces facing each other are surfaces parallel to the electric field direction of the electromagnetic wave. (E surface).

In the case where the inner shape of the electromagnetic wave radiating rectangular waveguide 22 (sectional shape), the depth direction length x ₁ is longer longitudinal rectangular shape than the width direction length x _2, the electromagnetic wave distribution for rectangular inner shape of the waveguide 21 (the cross-sectional shape) is also preferably set to the depth direction of the length y ₁ is greater longitudinal rectangular shape than the width direction length y _2. In the electromagnetic wave distribution rectangular waveguide 21 formed in this way, the bottom surface and the top surface are E planes parallel to the electric field direction of the electromagnetic wave, and a pair of side surfaces facing each other are perpendicular to the electric field direction of the electromagnetic wave. It becomes a surface.

  The electromagnetic wave transmission mechanism 3 is configured such that the central axis of the electromagnetic wave distribution rectangular waveguide 21 and the central axes of the three electromagnetic wave emission rectangular waveguides 22 are located on substantially the same plane, and the electromagnetic wave distribution rectangular waveguide is provided. The electromagnetic wave is configured to be distributed from the E surface of the wave tube 21 to each electromagnetic wave radiation rectangular waveguide 22. The electromagnetic wave transmission mechanism 3 may be configured such that each electromagnetic wave radiation rectangular waveguide 22 branches from the H surface of the electromagnetic wave distribution rectangular waveguide 21.

  Further, in the electromagnetic wave transmission mechanism 3, the inner shape dimension of the electromagnetic wave distribution rectangular waveguide 21 and the inner shape dimension of the electromagnetic wave radiation rectangular waveguide 22 are sizes in which only the fundamental mode in the rectangular waveguide is transmitted. It is set to become. Thus, by setting the inner dimensions of the rectangular waveguide 21 for electromagnetic wave distribution and the inner dimensions of the rectangular waveguide 22 for electromagnetic wave radiation to such a size that only the fundamental mode in the rectangular waveguide can be transmitted, the plasma is generated. The amount of propagation loss of the electromagnetic wave to be generated in the electromagnetic wave transmission mechanism 3 can be reduced.

By the way, in order to make the size that only the fundamental mode in the rectangular waveguide can be transmitted, the dielectric constant of the rectangular waveguide is ε, the major axis of the inner dimension of the rectangular waveguide is a, and the wavelength λ of the electromagnetic wave In addition,
(Λ / ε ^0.5 ) <2a (1)
This can be realized by designing so as to satisfy the above condition. As described above, the electromagnetic wave distribution rectangular waveguide 21 is filled with air (ε = 1), and the electromagnetic wave emission rectangular waveguide 22 is filled with the dielectric member 31 (synthetic quartz, ε = 3). .8).

Accordingly, inner dimensions of electromagnetic radiation for the rectangular waveguide 22 (minor diameter x ₁ and major axis x _2), the inner dimensions of the electromagnetic wave distribution for rectangular waveguide 21 (minor axis y ₁ and major axis y ₂₎ Dielectric The size needs to be divided by the square root of the dielectric constant ε of the body member 31. Specifically, since synthetic quartz has a dielectric constant ε of about 4, the minor axis x ₁ and the major axis x ₂ of the electromagnetic wave radiation rectangular waveguide 22 are the minor axis y of the electromagnetic wave distributing rectangular waveguide 21. it is necessary to make the _first and major axis y ₂ respectively about half the length.

  Therefore, in the plasma processing apparatus 1, the electromagnetic wave distribution rectangular waveguide 21 and the electromagnetic wave emission rectangular waveguide 22 are formed in a hollow first shape so that the inner dimension becomes smaller toward the electromagnetic wave transmission side. 3 are connected via an electromagnetic wave transmission line 3c. In the present embodiment, as shown in FIG. 1, each of the distribution pipe portions 21 b of the electromagnetic wave distribution rectangular waveguide 21 and each of the electromagnetic wave emission rectangular waveguides 22 includes a third electromagnetic wave having a connection member 50. The transmission line 3c is configured to be connected.

Hereinafter, with reference to FIG. 4 and FIG. 5, a connection mechanism between each distribution pipe portion 21 b of the electromagnetic wave distribution rectangular waveguide 21 and each electromagnetic wave emission rectangular waveguide 22 will be described.
The recess 23 provided in the lid 12 of the vacuum vessel 4 is also opened on the peripheral wall side of the lid 12. Each distribution pipe portion 21b of the electromagnetic wave distribution rectangular waveguide 21 is communicated with each electromagnetic wave emission rectangular waveguide 22 through the third electromagnetic wave transmission path 3c and the opening of the peripheral wall of the lid 12. It has become. The dielectric member 31 provided in the electromagnetic wave radiation rectangular waveguide 22 extends to the opening end of the peripheral wall of the lid 12.

  Each of the third electromagnetic wave transmission lines 3c includes a wedge-shaped dielectric member 42 formed integrally with the sealing member 41, a connection member 50, a first flange 51, a second flange 52, and It has a third flange 53, a first O-ring 54, and a second O-ring 55.

  The sealing member 41 and the wedge-shaped dielectric member 42 can be formed of a dielectric material such as quartz, alumina, and fluororesin, for example. In the present embodiment, the sealing member 41 and the wedge-shaped dielectric member 42 are made of synthetic quartz, like the dielectric member 31 provided in the second electromagnetic wave transmission path 3b.

As shown in FIG. 5, the wedge-shaped dielectric member 42 is formed in a wedge shape having a substantially isosceles side shape that expands toward the electromagnetic wave transmission side. The length m ₁ along the transmission direction of the wedge-shaped dielectric member 42 is set to be longer than the wavelength of the electromagnetic wave generated by the high-frequency power source 2 in vacuum. Therefore, in this plasma processing apparatus 1, as shown in FIG. 4, the end of the first electromagnetic wave transmission path 3a on the transmission side and the end of the second electromagnetic wave transmission path 3b opposite to the transmission side are Is longer than the wavelength of the electromagnetic wave generated by the high-frequency power source 2 in vacuum. Further, as shown in FIG. 5, the length m ₂ of the apex side 42a of the wedge-shaped dielectric member 42 is the long side of the inner shape of the electromagnetic wave radiation rectangular waveguide 22 included in the second electromagnetic wave transmission path 3b. It is set to be a length substantially the same length as x _2.

  As shown in FIGS. 4 and 5, a rectangular columnar sealing member 41 is integrally provided at an end portion on the transmission side of the wedge-shaped dielectric member 42. A groove 41a is formed in the sealing member 41 along the circumferential direction. The sealing member 41 may be formed integrally with the dielectric member 31 provided in the second electromagnetic wave transmission path 3b (the electromagnetic wave radiation rectangular waveguide 22). Further, the sealing member 41, the wedge-shaped dielectric member 42, and the dielectric member 31 in the second electromagnetic wave transmission path may all be integrally formed.

As the connection member 50, for example, a substantially conical tube having a taper such that the inner dimension becomes smaller toward the electromagnetic wave transmission side can be used. The inner dimension of the end of the connection member 50 on the electromagnetic wave transmission side is formed to be approximately the same as the cross-sectional dimension of the sealing member 41. Further, a flange 50a corresponding to the flange 21c provided at the tip of the distribution pipe portion 21b of the electromagnetic wave distribution rectangular waveguide 21 is provided at the end of the connection member 50 opposite to the electromagnetic wave transmission side. ing. By fixing the flange 21c and the flange 50a to each other, the electromagnetic wave distribution rectangular waveguide 21 and the connection member 50 are connected to each other. As shown in FIG. 4, the length t, wherein along the transmission direction of the connecting member 50, except the flange 51a becomes the along the transmission direction length m ₁ and substantially the same length of the dielectric member 42 of the wedge-shaped Is set to

  The first to third flanges 51, 52, 53 have a through hole having substantially the same size as the cross-sectional dimension of the sealing member 41. In the third electromagnetic wave transmission path 3 c, the connecting member 50, the first flange 51, the second flange 52, and the third flange 53 are arranged side by side in this order from the first electromagnetic wave transmission path 3 a side. . The first flange 51 is formed integrally with the connection member 50. Further, the end face on the transmission side of the first flange 51 has a concave portion 57, and the convex portion 58 that fits the concave portion 57 on the end face on the opposite side to the transmission side of the second flange 52. Is formed. The second flange 52 is fixed (positioned) to the first flange 51 by fitting the convex portion 58 into the concave portion 57. Further, a convex portion 59 is formed on the transmission-side end surface of the third flange 53, and the outer surface of the peripheral wall of the lid 12 has a concave portion 60 that fits the convex portion 59. The third flange 53 is fixed (positioned) with respect to the lid 12 by fitting the convex portion 59 into the concave portion 60. Further, the first flange 51, the second flange 52, and the third flange 53 are screwed to the lid 12 of the vacuum vessel 4 with screws 56 as fixtures. By doing in this way, the vacuum vessel 4 and the connection member 50 are mutually connected on both sides of the flanges 51-52. The connecting member 50 and the first flange 51 may be formed separately.

  In the third electromagnetic wave transmission path 3c, a sealing member 41 is disposed in the first to third flanges 51 to 53, and a wedge-shaped dielectric member 42 formed integrally with the sealing member 41 is connected to the third electromagnetic wave transmission path 3c. It is arranged in the member 50. The end of the sealing member 41 on the transmission side is in contact with the end of the dielectric member 31 provided in the second electromagnetic wave transmission path 3b on the side opposite to the transmission side.

The wedge-shaped dielectric member 42 is arranged such that the top side 42a is positioned in the vicinity of the end of the electromagnetic wave distribution rectangular waveguide 21 (the transmission-side tip of the distribution pipe 21b). The dielectric member 42 of the wedge-shaped, the top side 42a is the second substantially parallel to the long side x ₂ direction inner dimensions of electromagnetic wave transmission line electromagnetic wave radiation for a rectangular waveguide 22 3b has As shown in FIG.

  The sealing member 41 provided in the first to third flanges 51 to 53 has the first O-ring 54 provided along the groove 41 a on the inner wall surface of the second and third flanges 52 and 53. By pressing, airtightness between the second and third flanges 52 and 53 and the sealing member 41 is maintained. By doing in this way, the airtightness of the vacuum vessel 4 can be maintained.

  The connecting member 50, the first flange 51, the second flange 52, and the third flange 53 are made of a conductive material. Therefore, if the distance between the electromagnetic wave transmission mechanism 3 (the second and third flanges 52 and 53) and the sealing member 41 exceeds 1 mm, abnormal discharge may occur between the electromagnetic wave transmission mechanism 3 and the sealing member 41. There is. Therefore, the distance between the second and third flanges 52 and 53 and the sealing member 41 is preferably 1 mm or less.

  Moreover, the inside of the 1st thru | or 3rd flanges 51-53 is cut | interrupted by making the inner shape of the 1st thru | or 3rd flanges 51-53 substantially correspond with the inner shape (cross-sectional shape) of the sealing member 41. It can be filled with a dielectric material (sealing member 41) without any material. That is, the inside of the first to third flanges 51 to 53 is a rectangular waveguide in which a dielectric material is built, and the reflection of electromagnetic waves can be substantially zero in the inside. In addition, the reflection which arises between the 2nd and 3rd flanges 52 and 53 and the groove | channel of the 1st O-ring 54 can be suppressed by making the groove | channel 41a shallow.

  Further, in the plasma processing apparatus 1 of the present embodiment, a ring-shaped groove 61 facing the end surface of the third flange 53 is provided on the outer surface of the peripheral wall of the lid 12, and the second O-ring 55 is provided in the groove 61. By providing this, airtightness between the third flange 53 of the third electromagnetic wave transmission path 3c and the lid 12 of the vacuum vessel 4 is maintained.

  Each electromagnetic wave radiation rectangular waveguide 22 is coupled to the high-frequency power source 2 via an electromagnetic wave distribution rectangular waveguide 21 for distributing electromagnetic waves to the rectangular waveguides 22. As the high frequency power source 2, for example, a power source that supplies an electromagnetic wave having a frequency of 10 MHz to 25 GHz to the electromagnetic wave transmission mechanism 3 can be used. In the present embodiment, as the high-frequency power source 2, one microwave source that supplies an electromagnetic wave having a frequency of 2.45 GHz ± 50 MHz to the electromagnetic wave transmission mechanism 3 is employed. The high frequency power supply 2 having a frequency of 2.45 GHz is preferable because it is mass-produced, is inexpensive, and has a wide variety of types.

  As described above, in this plasma processing apparatus 1, a plurality of (three in this embodiment) rectangular waveguides 22 for electromagnetic wave radiation are supplied from one high-frequency power supply 2 through the rectangular waveguides 21 for electromagnetic wave distribution. Electromagnetic waves are supplied. Thus, the electromagnetic wave thrown into the electromagnetic wave radiation rectangular waveguide 22 is radiated into the vacuum container 4 from the slot 15a. The electromagnetic wave remaining without being radiated is finally reflected by the third flange 53 and radiated again into the vacuum vessel 4 through the slot 15a when returning.

  Therefore, since the frequency can be made the same in the whole area of the electromagnetic wave transmission mechanism 3, it is easy to design an electromagnetic wave radiation portion (slot plate 14) that emits a uniform energy density.

  Further, a cooling pipe as a cooling mechanism may be provided in a region corresponding to the space between the adjacent slots 15a in the wall of the vacuum vessel 4. By doing so, the electromagnetic wave transmission mechanism 3 (the electromagnetic wave radiation rectangular waveguide 22) can be efficiently cooled without hindering the generation of plasma.

  If this plasma processing apparatus 1 is used, the to-be-processed object 5 can be plasma-oxidized on surface wave plasma conditions, for example. Further, if this plasma processing apparatus 1 is used, for example, a plasma film can be formed on the object 5 under surface wave plasma conditions. Furthermore, if this plasma processing apparatus 1 is used, the to-be-processed object 5 can be plasma-etched on surface wave plasma conditions. Moreover, if this plasma processing apparatus 1 is used, plasma oxidation and film formation by plasma CVD can be performed continuously without breaking the vacuum. Hereinafter, as an example of a plasma processing method for the object 5 to be processed, a plasma processing method in which plasma oxidation and film formation by the plasma CVD method are performed without breaking the vacuum will be described.

  For example, a silicon substrate is prepared as the object 5 to be processed. The object to be processed 5 is provided on a support base 17 in the vacuum vessel 4. An evacuation system is operated and the air in the vacuum vessel 4 (inside the processing chamber 4a) is discharged. Thereafter, the first gas is supplied into the vacuum container 4 through the gas inlet 18. As the first gas, for example, oxygen gas or a mixed gas of oxygen and a rare gas containing at least one of helium, neon, argon, krypton, and xenon is used. In the present embodiment, oxygen gas is employed as the first gas, and this gas is supplied into the vacuum vessel 4 so that the oxygen gas is 400 SCCM and the total pressure is 20 Pa.

  After the gas pressure in the vacuum container 4 reaches a predetermined gas pressure, irradiation with electromagnetic waves is started. The electromagnetic wave sent to the slot 15a via the electromagnetic wave transmission mechanism 3 is radiated into the vacuum container 4 from each slot 15a.

  The electromagnetic wave radiated into the vacuum vessel 4 excites oxygen gas as the first gas. When the electron density in the plasma in the vicinity of the dielectric member 16 to be coated increases to a certain extent, the electromagnetic wave cannot propagate in the plasma and attenuates in the plasma. Therefore, the electromagnetic wave does not reach the area away from the clothing dielectric member 16, and surface wave plasma is generated in the vicinity of the clothing dielectric member 16.

  In the state where the surface wave plasma is generated, a high electron density is achieved in the vicinity of the dielectric member 16 to be coated, and accordingly, high-density oxygen atom active species are generated. This high-density oxygen atom active species diffuses to the object 5 to be processed, and the object 5 is efficiently oxidized. As a result, a first insulating film is formed on the surface of the object 5 to be processed. In the state in which surface wave plasma is generated, the electron temperature in the vicinity of the surface of the object to be processed 5 is low (electron energy is low), so the electric field of the sheath in the vicinity of the surface of the object to be processed 5 is also weak. Accordingly, since the incident energy of ions to the object to be processed 5 is reduced, ion damage of the object to be processed 5 during the oxidation process is suppressed.

  Further, the second gas is supplied from the gas inlet 18 into the vacuum container 4. As the second gas, for example, silane, an organic silicon compound (tetraalkoxysilane, vinylalkoxysilane, alkyltrialkoxysilane, phenyltrialkoxysilane, polymethyldisiloxane, polymethylcyclotetrasiloxane, etc.), or an organic metal A gas containing a compound (trimethylaluminum, triethylaluminum, tetrapropoxyzirconium, pentaethoxytantalum, tetrapropoxyhafnium, or the like) can be used. In the present embodiment, oxygen gas is continuously used as the first gas, and tetraethoxysilane gas, which is a kind of tetraalkoxysilane, is used as the second gas. Then, these gases are supplied into the vacuum vessel 4 so that the oxygen gas as the first gas is 400 SCCM, the tetraethoxysilane gas as the second gas is 10 SCCM, and the total pressure is 20 Pa.

  Oxygen radicals generated from the first gas react with tetraethoxysilane as the second gas. Thereby, decomposition of tetraethoxysilane is promoted, and silicon oxide is deposited on the surface of the object 5 to be processed. As a result, a second insulating film (silicon oxide film formed by CVD) is formed on the first insulating film. Thus, the formation of the insulating film on the object 5 is completed. According to this plasma processing method, after the object 5 is oxidized, the film forming process can be performed without exposure to the atmosphere. Therefore, the interface between the object to be processed and the film can be a good interface with little contamination, and a CVD film with good quality can be formed on the object to be processed 5.

  As described above, in the plasma processing apparatus 1 of the present embodiment, since the dielectric member 31 is provided inside the electromagnetic wave radiation rectangular waveguide 22, the plasma generated in the vacuum vessel 4 is transmitted to the electromagnetic wave transmission mechanism. 3 can be prevented from entering.

  Moreover, in the plasma processing apparatus 1 of the present embodiment, the electromagnetic wave (microwave) sent through the first electromagnetic wave transmission path 3a is sent to the second electromagnetic wave transmission path 3b without being reflected as much as possible. It is configured as follows. That is, the electromagnetic wave distributing rectangular waveguide 21 and each electromagnetic wave radiating rectangular waveguide 22 are connected by the third electromagnetic wave transmission path 3c in a shape whose inner dimension is changed with respect to the transmission direction of the electromagnetic wave. The wedge-shaped dielectric member 52 is installed in the connection member 50 of the third electromagnetic wave transmission path 3c. As a result, the electromagnetic wave is reflected by the change in the cross-sectional area of the rectangular waveguide, and the electromagnetic wave is reflected at the interface between the air and the dielectric member 42, or at the interface between the sealing member 41 made of a dielectric material and the dielectric member 31. Can be suppressed. Therefore, electromagnetic waves can be efficiently radiated into the vacuum container 4.

  Further, according to the plasma processing apparatus 1, the lid 12 as the wall of the vacuum vessel 4 has the electromagnetic wave radiation rectangular waveguide 22 that is at least a part of the electromagnetic wave transmission mechanism 3 that transmits electromagnetic waves. Therefore, according to the plasma processing apparatus 1, the structure can be simplified. Further, uniform plasma can be generated in a large area in the vacuum vessel 4. In addition, even the object 5 to be processed such as a square substrate or a large-area substrate can be satisfactorily plasma-treated.

  Furthermore, according to the plasma processing apparatus 1, an electromagnetic wave transmission window for allowing electromagnetic waves to enter the vacuum vessel 4 can be omitted from the vacuum vessel 4. In addition, the sealing part for holding the vacuum of the vacuum vessel 4 is only a connecting part for connecting the electromagnetic wave distribution rectangular waveguide 21 and the vacuum container 4, a connecting part for connecting the lid 12 and the container body 11, and the like. It's okay. Therefore, in the plasma processing apparatus of the present embodiment, the number of seals can be reduced compared to the conventional plasma processing apparatus.

  Moreover, according to the plasma processing apparatus 1 of this embodiment, the to-be-processed object 5 can be plasma-processed by surface wave plasma with little ion damage.

  The plasma processing apparatus and the plasma processing method of the present invention are not limited to the above-described embodiments, and can be implemented in various ways without departing from the gist thereof.

1 is a top view showing a plasma processing apparatus according to a first embodiment of the present invention. The figure which shows the plasma processing apparatus of FIG. 1 in cross section along the direction which crosses the rectangular waveguide for electromagnetic wave radiation. The figure which shows the plasma processing apparatus of FIG. 1 in cross section along the rectangular waveguide direction for electromagnetic wave radiation. Sectional drawing which expands and shows the 3rd electromagnetic wave transmission path vicinity of the plasma processing apparatus of FIG. The perspective view which shows the dielectric material with which the 3rd electromagnetic wave transmission path vicinity of the plasma processing apparatus of FIG. 1 is provided.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Plasma processing apparatus, 2 ... High frequency power supply (oscillator), 3a ... 1st electromagnetic wave transmission path, 3b ... 2nd electromagnetic wave transmission path, 3c ... 3rd electromagnetic wave transmission path, 4 ... Vacuum container (processing container), DESCRIPTION OF SYMBOLS 14 ... Electromagnetic radiation part (slot board), 31 ... Dielectric member, 41 ... Sealing member, 42 ... Wedge-shaped dielectric member

Claims (9)

A processing vessel;
An oscillator that oscillates electromagnetic waves;
A first electromagnetic wave transmission line;
A second electromagnetic wave transmission path in which an inner shape dimension is set smaller than that of the first electromagnetic wave transmission path, and a dielectric member is provided inside;
Provided in the second electromagnetic wave transmission path, comprising an electromagnetic wave radiation part for radiating electromagnetic waves in the processing container,
An electromagnetic wave generated by the oscillator is introduced into the second electromagnetic wave transmission path via the first electromagnetic wave transmission path and is radiated into the processing container by the electromagnetic wave radiation unit, thereby the processing container. A plasma processing apparatus in which plasma is generated and plasma processing is performed by this plasma,
The first electromagnetic wave transmission line and the second electromagnetic wave transmission line are connected via a hollow third electromagnetic wave transmission line formed so that the inner dimension is reduced toward the electromagnetic wave transmission side. And a wedge-shaped dielectric member arranged so as to expand toward the transmission side inside the third electromagnetic wave transmission path.   2. The wedge-shaped dielectric member is disposed so that a top side thereof is positioned at an end portion on the transmission side of the first electromagnetic wave transmission path or a region in the vicinity thereof. The plasma processing apparatus as described.   The plasma processing apparatus according to claim 1, wherein the processing container is hermetically sealed by the wedge-shaped dielectric member or the dielectric member in the second electromagnetic wave transmission path.   The distance between the end of the first electromagnetic wave transmission line on the transmission side and the end of the second electromagnetic wave transmission line opposite to the transmission side is in a vacuum of electromagnetic waves generated by the oscillator. 4. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is set to be longer than the wavelength of the plasma processing apparatus.   5. The plasma processing apparatus according to claim 1, wherein each of the first and second electromagnetic wave transmission lines has a rectangular waveguide. 6.   The inner dimension of the rectangular waveguide included in the first electromagnetic wave transmission line and the inner dimension of the rectangular waveguide included in the second electromagnetic wave transmission path are respectively determined such that the frequency of the electromagnetic wave generated by the oscillator is rectangular. 6. The plasma processing apparatus according to claim 5, wherein the plasma processing apparatus is set to a size capable of transmitting in the fundamental mode in the waveguide. The length of the top side of the wedge-shaped dielectric member is set to be substantially the same as the length of the inner long side of the rectangular waveguide included in the second electromagnetic wave transmission path. With
The wedge-shaped dielectric member has a top side substantially parallel to the long side direction of the inner diameter of the rectangular waveguide included in the second electromagnetic wave transmission line, and a line connecting the midpoints of the short sides. The plasma processing apparatus according to claim 5, wherein the plasma processing apparatus is substantially disposed on the plasma processing apparatus.   The length along the transmission direction of the electromagnetic wave of the wedge-shaped dielectric member is set to be longer than the wavelength of the electromagnetic wave generated by the oscillator in vacuum. The plasma processing apparatus of any one of these.   The plasma processing apparatus according to claim 1, wherein a wall of the processing container has at least a part of the second electromagnetic wave transmission path.

Images